Concept:Convection is the main mode of heat transfer in liquids and gases.
Explanation:Water is a liquid, so heat transfer inside it occurs mainly by convection.
The gas stove heats the bottom of the bowl first.
The heated water at the bottom becomes lighter and rises.
The cooler water from the top moves down to take its place.
This continuous circulation of water is called a convection current.
Through this process, the whole bowl of water becomes warm.
Conduction is mainly in solids, and radiation does not need a medium.
Answer:A. Convection